How are quantum mechanics and philosophy connected?

Philosophy of Science: Physicists are philosophers too

The metaphysics in the armchair is really dead

The advocates of a Platonic view of reality are therefore insincere when they demean philosophy. After all, they adopt the teaching of one of the most influential philosophers of all time. That makes them philosophers too. Not all physicists who criticize philosophers are also staunch Platonists. Nevertheless, many of them are close to this position when they talk about the mathematical elements of their models and the laws they have discovered as if they were built into the structure of the universe. In fact, Weinberg, Hawking, Mlodinow, Krauss, and Tyson should rather address their objections to metaphysics. In addition, from our point of view, they show too little appreciation for the essential contributions to human thinking in areas such as ethics, aesthetics, politics and, perhaps most importantly, epistemology. Krauss pays lip service to these important topics, but doesn't seem particularly enthusiastic.

A sound philosophy in physics

Hawking and Mlodinow write their texts mostly against the background of cosmological questions - and when they reach for metaphysics to deal with the question of the origin of everything, they behave absolutely correctly. Because metaphysics and its protocosmological speculations, understood as philosophy, were seen as the handlers of theology in the Middle Ages. According to Hawking and Mlodinow, metaphysicians who want to deal with cosmological questions are not scientifically well-versed enough to make a meaningful contribution. As for cosmology, armchair metaphysics is really dead and has been replaced by a well-founded philosophy of physics. Apart from theologians, few would disagree with this statement.

Krauss directs his sharp criticism of the philosophy of science. In our view, it would have been more constructive if he had targeted certain aspects of metaphysics. In an interview for "The Atlantic" Andersen asked him if physics had made philosophy and religion obsolete. And even if this does not apply to philosophy, it does apply to cosmological metaphysics (and the religious claims based on it - such as the cosmological Kalam proof of God). Krauss certainly used metaphysical approaches, at least in part, to speculate about the universe; after all, the interview was about his book on cosmology.

Whatever branches of philosophy may deserve the appreciation of scientists and the public, metaphysics is not one of them. The problem is obvious. Metaphysics claims to be directly related to reality - that is, to legitimately describe reality - but there is no way of verifying this. The well-known physicists we have mentioned here, as well as everyone else from this camp, are entitled to speak condescendingly about cosmological metaphysics. But if you think you have completely detached yourself from philosophy, in our opinion you are utterly mistaken. First, those who view mathematical objects as real in their models try Platonic metaphysics - consciously or unconsciously. Second, those who do not yet fully identify with Platonism still allow epistemological considerations to flow into their explanations. Because they insist that observation is our only source of knowledge.

Hawking and Mlodinow clearly reject Platonism when they say: "There is no concept of reality independent of images or theories." Instead, the two advocate a philosophical teaching they call model-dependent realism. By this they understand "the view that a physical theory or a worldview consists of a model (mostly of a mathematical nature) and a series of laws that link elements of the model with observations". In doing so, they clearly indicate that "it is pointless to ask whether a model is real, only whether it agrees with the observations".

We are unclear how model-dependent realism differs from instrumentalism. In both cases, physicists only deal with observations and, although they do not deny that they arise from a fundamental reality, they do not insist that the models describing those observations must correspond exactly to that reality. Either way, Hawking and Mlodinow act as philosophers - or at least epistemologists - in discussing what we can know about basic reality, even if their ultimate answer is "nothing".

All of the prominent critics of philosophy whose views we have discussed here ponder carefully the source of human knowledge. So you are all epistemologists. At best, they could claim that they understand more about science than (most) professional philosophers and that they rely on observation and experiment instead of pure thought - but not that they do not philosophize. Philosophy is certainly not dead. This statement applies more to forms of pure thought, such as those that include cosmological metaphysics.

Editor's note: The well-known physicist and intellectual Victor Stenger died in August last year at the age of 79. Shortly before his death, he worked with two co-authors on an article for the "Scientific American". In it, Stenger and his colleagues deal with the latest developments in an ongoing historical controversy - a dispute between physicists and philosophers about the nature of their disciplines and the limits of science. This article is the last that Stenger penned.